This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Visible light-absorbing polynuclear charge-transfer sites anchored on the pore surface of high surface area mesoporous silica afford splitting of carbon dioxide to CO. Polynuclear water oxidation catalysts can be covalently linked to metal centers embedded in the silica pore surface for oxygen evolution under visible light. Evidence for covalent anchoring on the silica surface and connection of the metal centers through an O bridge was obtained by FT-infrared, FT-Raman and optical spectroscopy. In order to reach our long term goal of coupling the photocatalytic components of the half reactions to build integrated units in these nanoporous scaffolds that reduced CO2 by H2O under visible light, a more detailed structural understanding of the redox sites is essential. Therefore, XAS studies are proposed with the goal of elucidating the coordination environment of the metal centers of the binuclear charge-transfer chromophores, and the precise structure of the linkage between the donor metal center and the catalytic core of the water oxidation catalyst.